Merge pull request #9907 from afvincent/enh_annotated_bar_example

jklymak · web-flow · commit dbe0502db6a0 · 2017-12-01T14:08:59.000-08:00
DOC: (subjectively) nicer annotated barchart example
diff --git a/examples/api/barchart.py b/examples/api/barchart.py
@@ -3,45 +3,50 @@
 Barchart
 ========
 
-A bar plot with errorbars and height labels on individual bars
+A bar plot with errorbars and height labels on individual bars.
 """
 import numpy as np
 import matplotlib.pyplot as plt
 
-N = 5
-men_means = (20, 35, 30, 35, 27)
-men_std = (2, 3, 4, 1, 2)
+men_means, men_std = (20, 35, 30, 35, 27), (2, 3, 4, 1, 2)
+women_means, women_std = (25, 32, 34, 20, 25), (3, 5, 2, 3, 3)
 
-ind = np.arange(N)  # the x locations for the groups
-width = 0.35       # the width of the bars
+ind = np.arange(len(men_means))  # the x locations for the groups
+width = 0.35  # the width of the bars
 
 fig, ax = plt.subplots()
-rects1 = ax.bar(ind, men_means, width, color='r', yerr=men_std)
+rects1 = ax.bar(ind - width/2, men_means, width, yerr=men_std,
+                color='SkyBlue', label='Men')
+rects2 = ax.bar(ind + width/2, women_means, width, yerr=women_std,
+                color='IndianRed', label='Women')
 
-women_means = (25, 32, 34, 20, 25)
-women_std = (3, 5, 2, 3, 3)
-rects2 = ax.bar(ind + width, women_means, width, color='y', yerr=women_std)
-
-# add some text for labels, title and axes ticks
+# Add some text for labels, title and custom x-axis tick labels, etc.
 ax.set_ylabel('Scores')
 ax.set_title('Scores by group and gender')
-ax.set_xticks(ind + width / 2)
+ax.set_xticks(ind)
 ax.set_xticklabels(('G1', 'G2', 'G3', 'G4', 'G5'))
-
-ax.legend((rects1[0], rects2[0]), ('Men', 'Women'))
+ax.legend()
 
 
-def autolabel(rects):
+def autolabel(rects, xpos='center'):
     """
-    Attach a text label above each bar displaying its height
+    Attach a text label above each bar in *rects*, displaying its height.
+
+    *xpos* indicates which side to place the text w.r.t. the center of
+    the bar. It can be one of the following {'center', 'right', 'left'}.
     """
+
+    xpos = xpos.lower()  # normalize the case of the parameter
+    ha = {'center': 'center', 'right': 'left', 'left': 'right'}
+    offset = {'center': 0.5, 'right': 0.57, 'left': 0.43}  # x_txt = x + w*off
+
     for rect in rects:
         height = rect.get_height()
-        ax.text(rect.get_x() + rect.get_width()/2., 1.05*height,
-                '%d' % int(height),
-                ha='center', va='bottom')
+        ax.text(rect.get_x() + rect.get_width()*offset[xpos], 1.01*height,
+                '{}'.format(height), ha=ha[xpos], va='bottom')
+
 
-autolabel(rects1)
-autolabel(rects2)
+autolabel(rects1, "left")
+autolabel(rects2, "right")
 
 plt.show()
